Apparatus, systems, and methods for  providing location information

ABSTRACT

The disclosed apparatus, systems, and methods relate to a location query mechanism that can efficiently determine whether a target entity is located within a region of interest (ROI). At a high level, the location query mechanism can be configured to represent a ROI using one or more polygons. The location query mechanism can, in turn, divide (e.g., tessellate) the one or more polygons into sub-polygons. Subsequently, the location query mechanism can use the sub-polygons to build an index system that can efficiently determine whether a particular location is within any of the sub-polygons. Therefore, when a computing device queries whether a particular location is within the region of interest, the location query mechanism can use the index system to determine whether the particular location is within any of the sub-polygons.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/367,161, filed Mar. 27, 2019, which is a continuation of Ser. No.16/006,748, filed Jun. 12, 2018, now U.S. Pat. No. 10,268,708, which isa continuation of U.S. patent application Ser. No. 15/673,349, filedAug. 9, 2017, now U.S. Pat. No. 10,013,446, which is a continuation ofU.S. patent application Ser. No. 14/214,296, filed Mar. 14, 2014, nowU.S. Pat. No. 9,753,965, entitled “APPARATUS, SYSTEMS, AND METHODS FORPROVIDING LOCATION INFORMATION”, which claims the benefit of the earlierfiling date under 35 U.S.C. § 119(e), of:

-   -   U.S. Provisional Application No. 61/799,986, filed on Mar. 15,        2013, entitled “SYSTEM FOR ANALYZING AND USING LOCATION BASED        BEHAVIOR;”    -   U.S. Provisional Application No. 61/800,036, filed on Mar. 15,        2013, entitled “GEOGRAPHIC LOCATION DESCRIPTOR AND LINKER;”    -   U.S. Provisional Application No. 61/799,131, filed on Mar. 15,        2013, entitled “SYSTEM AND METHOD FOR CROWD SOURCING DOMAIN        SPECIFIC INTELLIGENCE;”    -   U.S. Provisional Application No. 61/799,846, filed Mar. 15,        2013, entitled “SYSTEM WITH BATCH AND REAL TIME DATA        PROCESSING;” and    -   U.S. Provisional Application No. 61/799,817, filed on Mar. 15,        2013, entitled “SYSTEM FOR ASSIGNING SCORES TO LOCATION        ENTITIES.”

This application is also related to:

-   -   U.S. patent application Ser. No. 14/214,208, filed on Mar. 14,        2014, now U.S. Pat. No. 9,594,791, entitled “APPARATUS, SYSTEMS,        AND METHODS FOR ANALYZING MOVEMENTS OF TARGET ENTITIES;”    -   U.S. patent application Ser. No. 14/214,213, filed on Mar. 14,        2014, entitled “APPARATUS, SYSTEMS, AND METHODS FOR        CROWDSOURCING DOMAIN SPECIFIC INTELLIGENCE;”    -   U.S. patent application Ser. No. 14/214,219, filed on Mar. 14,        2014, now U.S. Pat. No. 9,317,541, entitled “APPARATUS, SYSTEMS,        AND METHODS FOR BATCH AND REALTIME DATA PROCESSING;”    -   U.S. patent application Ser. No. 14/214,309, filed on Mar. 14,        2014, now U.S. Pat. No. 10,331,631, entitled “APPARATUS,        SYSTEMS, AND METHODS FOR ANALYZING CHARACTERISTICS OF ENTITIES        OF INTEREST;” and    -   U.S. patent application Ser. No. 14/214,231, filed on Mar. 14,        2014, entitled “APPARATUS, SYSTEMS, AND METHODS FOR GROUPING        DATA RECORDS.”

The entire content of each of the above-referenced applications(including both the provisional applications and the non-provisionalapplications) is herein incorporated by reference.

FIELD OF THE INVENTION

The present disclosure generally relates to data processing systems, andspecifically, to data processing systems that can provide information ongeographic location of an entity.

BACKGROUND

As location-aware devices, such as Global Positioning System(GPS)-enabled mobile phones, have become popular over the years, it isincreasingly desirable to quickly and efficiently determine whether adevice is within a region of interest. Similarly, developers ofsports-related mobile applications may wish to provide a differentinterface for users when users are inside a football stadium ortailgating in the stadium parking lot. Additionally, processing datawith location information from, for example, user logs, location taggedsocial network information (e.g. a stream of tweets from twitter), orsimilar data can benefit from additional contextual information such aswhether the stated location is in a region of interest such as ashopping mall. In such cases, it is desirable to: a) define region(s) ofinterest, b) determine whether a geographic location point (e.g.latitude and longitude) is within the region(s) of interest, c) if so,identify the region corresponding to the geographic location point, andd) based on the identified region, if any, determine an action to beperformed based on the identified region, such as a particularadvertisement, user interface, or other computer logic that should occurbased on the location being inside the region of interest.

SUMMARY

In general, in an aspect, embodiments of the disclosed subject mattercan include an apparatus. The apparatus includes a processor configuredto run one or more modules stored in memory. The one or more modules areconfigured to receive one or more polygons associated with a region ofinterest, determine a plurality of sub-polygons that are containedwithin the one or more polygons, wherein each of the sub-polygons isassociated with a unique code, and generate a first index system basedon at least a subset of the plurality of sub-polygons, thereby providingan efficient mechanism to determine whether a particular location iswithin the region of interest.

In general, in an aspect, embodiments of the disclosed subject mattercan include a method. The method includes receiving, at an indexgeneration module of a computing system, one or more polygons associatedwith the region of interest, determining, at the index generationmodule, a plurality of sub-polygons that are contained within the one ormore polygons, wherein each of the sub-polygons is associated with aunique code, and generating, at the index generation module, a firstindex system based on at least a subset of the plurality ofsub-polygons, thereby providing an efficient mechanism to determinewhether a particular location is within the region of interest.

In general, in an aspect, embodiments of the disclosed subject mattercan include a non-transitory computer readable medium. Thenon-transitory computer readable medium can include executableinstructions operable to cause a data processing apparatus to receiveone or more polygons associated with a region of interest, determine aplurality of sub-polygons that are contained within the one or morepolygons, wherein each of the sub-polygons is associated with a uniquecode, and generate a first index system based on the tree structure,thereby providing an efficient mechanism to search whether a particularlocation is within the region of interest.

In any one of the embodiments disclosed herein, the unique code canincludes a location identifier based on a hierarchical encoding scheme,such as, for example, a geohash code.

In any one of the embodiments disclosed herein, the index can includeone of a hash table or a probabilistic data structure.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for determining a differencebetween the index system and a previously-generated index system, andproviding the difference to a computing device to update thepreviously-generated index system in the computing device.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for identifying a treestructure that models the unique code of the plurality of sub-polygonsbased on a hierarchy of the unique codes and generating the first indexsystem based on the tree structure.

In any one of the embodiments disclosed herein, the tree structure caninclude a branch node and a leaf node, and the branch node is associatedwith a geographic area that is larger than that of the leaf node, andwherein the apparatus, the method, or the non-transitory computerreadable medium further includes modules, steps, or executableinstructions for generating indices for the index system by traversingthe tree structure from the branch node to the leaf node.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for determining a list ofpolygons that includes a particular sub-polygon, and associating thelist of polygons with a leaf node of the tree structure corresponding tothe particular sub-polygon.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for merging the treestructure, corresponding to the region of interest, with a second treestructure corresponding to a second region of interest, therebyproviding a single index system modeling both the first tree structureand the second tree structure.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for removing one or moresub-polygons corresponding to a particular polygon from the indexsystem.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for removing one or moresub-polygons from the plurality of sub-polygons to provide a reduced setof sub-polygons and generating the index system from the reduced set ofsub-polygons, thereby reducing the size of the index system.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for receiving a second indexsystem from another computing device and merging the first index systemand the second index system by considering an overlap of sub-polygonscorresponding to the first index system and the second index system.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for providing the indexsystem to a computing device so that the computing device can use theindex system to serve location queries.

In general, in an aspect, embodiments of the disclosed subject mattercan include an apparatus, a method, and a non-transitory computerreadable medium. The apparatus, the method, or the non-transitorycomputer readable medium can include modules, steps, or executableinstructions for receiving a location query from the client device,wherein the location query includes a location identifier associatedwith the client device, determining a query identifier corresponding tothe location identifier, comparing the query identifier with the indexsystem to determine that the location identifier provided by the clientdevice is within the region of interest, and providing a serviceassociated with the region of interest to the client device over thecommunication network.

In any one of the embodiments disclosed herein, the unique identifiersand the query identifier can include geohash codes.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for determining that thequery identifier is represented in the index system and that thelocation identifier provided by the client device is within the regionof interest

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for comparing a firstsequence of bits of the query identifier, corresponding to alower-precision sub-polygon, to the index system before comparing asecond sequence of bits of the query identifier, corresponding to ahigher-precision sub-polygon.

In any one of the embodiments disclosed herein, wherein the index systemcomprises an index tree, and the apparatus, the method, or thenon-transitory computer readable medium further includes modules, steps,or executable instructions for determining that the query identifier iswithin the region of interest when the first sequence of bits of thequery identifier match a first index of the index system correspondingto a leaf node of the index system.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for retrieving, from theindex system, a polygon identifier associated with the query identifier,determining a group identifier associated with the polygon identifier,and providing the service associated with the campaign identifier to theclient device over the communication network.

In any one of the embodiments disclosed herein, the apparatus, themethod, or the non-transitory computer readable medium can includemodules, steps, or executable instructions for retrieving, from theindex system, a polygon identifier associated with the query identifier,and providing data associated with the polygon identifier to the clientdevice over the communication network.

DESCRIPTION OF THE FIGURES

Various objects, features, and advantages of the present disclosure canbe more fully appreciated with reference to the following detaileddescription when considered in connection with the following drawings,in which like reference numerals identify like elements. The followingdrawings are for the purpose of illustration only and are not intendedto be limiting of the disclosed subject matter, the scope of which isset forth in the claims that follow.

FIG. 1 illustrates a diagram of a location query system in accordancewith some embodiments.

FIGS. 2-3 illustrate how location identifiers can be used to represent aregion of interest in accordance with some embodiments.

FIGS. 4A-4B illustrate properties of geohash codes and tiles inaccordance with some embodiments.

FIG. 5 illustrates a tree of geohash codes in accordance with someembodiments.

FIGS. 6A-6D illustrate two collections of geohash tiles and theassociated tree in accordance with some embodiments.

FIGS. 7A-7C illustrate a merging of the trees in accordance with someembodiments.

FIGS. 8A-8B illustrate a mechanism for generating the geohash tile indexsystem in accordance with some embodiments.

FIG. 9 illustrates a process for serving location queries in accordancewith some embodiments.

FIG. 10 illustrates a process for comparing a query geohash code to ageohash index system in accordance with some embodiments.

FIGS. 11A-11B illustrates a process for comparing a geohash code and ageohash index system in accordance with some embodiments.

FIG. 12 illustrates a process for building an index system associatedwith a set of regions of interest in accordance with some embodiments.

FIGS. 13A-13D illustrate a process of building an index treecorresponding to a region in accordance with some embodiments.

FIG. 14 illustrates a process for responding to a location query inaccordance with some embodiments.

DETAILED DESCRIPTIONS

In the following description, numerous specific details are set forthregarding the systems and methods of the disclosed subject matter andthe environment in which such systems and methods may operate, etc., inorder to provide a thorough understanding of the disclosed subjectmatter. It will be apparent to one skilled in the art, however, that thedisclosed subject matter may be practiced without such specific details,and that certain features, which are well known in the art, are notdescribed in detail in order to avoid complication of the disclosedsubject matter. In addition, it will be understood that the examplesprovided below are exemplary, and that it is contemplated that there areother systems and methods that are within the scope of the disclosedsubject matter.

The disclosed apparatus, systems, and methods relate to a location querymechanism that can efficiently determine whether a target entity islocated within a region of interest (ROI). At a high level, the locationquery mechanism can be configured to represent a ROI using one or morepolygons. The location query mechanism can, in turn, divide (e.g.,tessellate) the one or more polygons into sub-polygons. Subsequently,the location query mechanism can use the sub-polygons to build an indexsystem that can efficiently determine whether a particular location iswithin any of the sub-polygons. Therefore, when a computing devicequeries whether a particular location is within the region of interest,the location query mechanism can use the index system to determinewhether the particular location is within any of the sub-polygons.

In some embodiments, the disclosed location query mechanism can includethree stages. The first stage includes representing the ROI with one ormore polygons. The second stage includes the generation of an indexsystem for the one or more polygons. The index system generation processcan involve receiving location descriptions of the one or more polygonsand generating an efficiently query-able data structure for the locationdescriptions. The index system generation process can be performedoff-line using a single computer or a cluster of computers. Therefore,the index system generation process may not interfere with an on-line(e.g., real-time) or high throughput (e.g. batch or real-time) operationof the location query response mechanism, as disclosed below.

The third, stage includes a real-time query response mechanism forresponding to location queries. For example, when the query responsemechanism receives a location query, including a location identifier,from a client device, the query response mechanism can search the indexsystem to determine whether the location identifier is associated withany of the polygons represented by the index system. If the locationidentifier is associated with one of the polygons, the query responsemechanism can indicate the one or more polygons associated with thelocation identifier.

The disclosed location query mechanism is substantially more efficientcompared to existing location query mechanisms. The disclosed locationquery mechanism can enable a server to serve queries in sub millisecondsand theoretically enable the processing of tens of thousands of queriesper second per processing core.

The disclosed location query mechanism can be useful in theadvertisement industry. For example, the advertisement display system ona mobile device can be configured to update and send the mobile device'sgeographic location information to an advertisement server. Theadvertisement server, in turn, can use the disclosed location querymechanism to identify relevant advertising campaigns related to thedevice's location, and use this information to serve highly contextual,location sensitive advertisement to the mobile device. Therefore, thequery response mechanism can cause an advertisement to be sent to atarget entity associated with the location identifier.

The disclosed location query mechanism can also be useful in mobileapplications services. For example, sports-related mobile applicationsmay provide a different interface on a user interface (e.g., a screen)of a mobile device depending on the device's location. For instance, amobile device can update and send its geographic location information tothe mobile application server. The mobile application server, in turn,can use the disclosed location query mechanism to identify relevantservices related to the device's location, and use this information toserve highly contextual, location sensitive service to the mobiledevice.

The disclosed location query mechanism can also be useful in a varietyof applications that processes data with location information. Forexample, processing data with location information from, for example,user logs, location tagged social network information (e.g. a stream oftweets), or similar data can benefit from additional contextualinformation such as whether the stated location is in a region ofinterest such as a shopping mall.

FIG. 1 illustrates a diagram of a location query system in accordancewith some embodiments. The system 100 includes a host server 102, acommunication network 104, and one or more client devices 106. The hostserver 102 can include a processor 108, a memory device 110, an indexgeneration module 112, and a query response module 114. The host server102 and the one or more client devices 106 can communicate via thecommunication network 104.

The communication network 104 can include the Internet, a cellularnetwork, a telephone network, a computer network, a packet switchingnetwork, a line switching network, a local area network (LAN), a widearea network (WAN), a global area network, or any number of privatenetworks currently referred to as an Intranet, and/or any other networkor combination of networks that can accommodate data communication. Suchnetworks may be implemented with any number of hardware and softwarecomponents, transmission media and network protocols. Although FIG. 1represents the network 104 as a single network, the network 104 caninclude multiple interconnected networks listed above.

A client 106 can include a desktop computer, a mobile computer, a tabletcomputer, a cellular device, or any other computing devices having aprocessor and memory. The client 106 can communicate with the hostserver 102 via the communication network 104. Although FIG. 1 representsthe host server 102 as a single server, the host server 102 can includemore than one server and can be part of a cloud-computing platform.

The processor 108 of the host server 102 can be implemented in hardware.The processor 108 can include an application specific integrated circuit(ASIC), programmable logic array (PLA), digital signal processor (DSP),field programmable gate array (FPGA), or any other integrated circuit.The processor 108 can also include one or more of any other applicableprocessors, such as a system-on-a-chip that combines one or more of aCPU, an application processor, and flash memory, or a reducedinstruction set computing (RISC) processor. The memory device 110 of theprocessor 108 can include a computer readable medium, flash memory, amagnetic disk drive, an optical drive, a programmable read-only memory(PROM), and/or a read-only memory (ROM).

The index generation module 112 can be configured to generate an indexsystem for one or more polygons. The index generation module 112 canmaintain the generated index in the memory device 110 or provide thegenerated index to the query response module 114. The query responsemodule 114 can be configured to respond to location queries inreal-time. In some cases, the query response module 114 can reside inthe host server 102. In other cases, the query response module 114 canreside in the client device 106. Also, the index generation module 112and the query response module 114 need not reside on the same device.

In some embodiments, the index generation module 112 and/or the queryresponse module 114 can be implemented in software stored in the memorydevice 110. The software stored in the memory device 110 can run on theprocessor 108 capable of executing computer instructions or computercode.

In some embodiments, the index generation module 112 and/or the queryresponse module 114 can be implemented in hardware using an ASIC, PLA,DSP, FPGA, or any other integrated circuit. In some embodiments, theindex generation module 112 and the query response module 114 can bothbe implemented on the same integrated circuit, such as ASIC, PLA, DSP,or FPGA, thereby forming a system on chip.

The index generation (“IG”) module 112 can be configured to use one ormore location identifiers to represent a polygon. Location identifierscan be associated with any coordinate systems or hashing systemsrepresenting a region. More particularly, a polygon can be tessellatedinto a set of tiles (also referred to as sub-polygons). Each sub-polygoncan cover geographic sub-region based on the desired level of precision,and can be associated with a location identifier. For example, alocation identifier can include geohash code associated with a region ofa predetermined precision, or size. A region associated with a locationidentifier can be referred to as a tile or a sub-polygon. For example, aregion associated with a geohash code can be referred to as a geohashtile or a geohash sub-polygon.

In some embodiments, location identifiers can be hierarchicallyorganized. For example, certain types of location identifiers, such asgeohash codes, can use a 32 subdivision system. Under the 32 subdivisionsystem, a geohash code can be associated with a region, that are coveredby 32 other geohash codes, and each of the 32 other geohash codes can,in turn, be associated with a region that are covered by a plurality ofother geohash codes. Therefore, the geohash codes can be represented asa tree. The hierarchy of the location identifiers can be determinedbased on a variety of factors, for example, a number of bits used torepresent a location identifier, a depth of the tree representing thehierarchy of location identifiers, and/or a breadth of the treerepresenting the hierarchy of location identifiers.

FIG. 2 illustrates how location identifiers can be used to represent apolygon in accordance with some embodiments. FIG. 2 includes a region ofinterest, which can include one or more polygons 200. A polygon canrefer a geographic demarcation of an area. In some embodiments, thepolygon can be represented graphically on a map; in other embodiments,the polygon can be represented by a plurality of subpolygons associatedwith location identifiers. For example, the polygon can be representedby a plurality of geohash tiles, including a first geohash tile 202 anda second geohash tile 204, each of which can be associated with ageohash code.

In some embodiments, a geohash tile can have one of severalpredetermined sizes. For example, the first geohash tile 202 is largerthan the second geohash tile 204. As shown, smaller, higher precision,geohash tiles are used near the periphery of the polygon and larger,lower precision, geohash tiles are used in the interior of the polygon.The area of the polygon 200 is taken to be the collective area definedby all the tiles that form the polygon.

FIG. 3 also illustrates how location identifiers can be used torepresent a polygon in accordance with some embodiments. FIG. 3 includesa region of interest, which is a polygon 300 having a circular shapesurrounding a point of interest at the center of the polygon 300. Aswith FIG. 2, the polygon 300 is represented by a plurality ofsubpolygons associated with location identifiers. For example, thepolygon 300 is represented by a plurality of geohash tiles, including afirst geohash tile 302 and a second geohash tile 304, and each geohashtile can be associated with one of several predetermined sizes. As withFIG. 2, smaller, higher precision, geohash tiles are used to define theperiphery of the polygon 300 and larger, lower resolution, geohash tilesare used in the interior of the polygon 300. Again, the area of thepolygon 300 is taken to be the collective area defined by all geohashtiles that form the polygon 300.

In some embodiments, the IG module 112 can be configured to identify oneor more sub-polygons (e.g., geohash tiles) that collectively represent aregion comprising a plurality of polygons. The sub-polygonidentification for a region can involve two steps. The first step of thesub-polygon identification can include receiving one or more polygonsassociated with a region. These polygons can be as simple as acoordinate (representing the location of a point-of-interest) enclosedby a circle of a given radius, or more complex shape, like a multi-edgedpolygon representing a desired geographical area, or apoint-of-interest, such as an airport.

The second step of the sub-polygon identification can include generatingone or more sub-regions that are enclosed by the region (e.g., assembledpolygons). For example, a geohash tile can be defined on a coordinatesystem, and can be considered a sub-region defined on that coordinatesystem. The IG module 112 can be configured to find sub-regions (e.g.,geohash tiles), defined on the geohash coordinate system, that areentirely contained within the one of the assembled polygons. The IGmodule 112 can be configured to favor a region representation that useslarger sub-regions than smaller sub-regions so that a polygon can berepresented with a small number of sub-regions.

The IG module 112 can be configured to identify such sub-polygons in aniterative manner. For example, as a first step, the IG module 112 can beconfigured to construct a set of geohash tiles having an identical,largest size such that this set of geohash tiles encompasses one or morepolygons in the region of interest. Subsequently, the IG module 112 canbe configured to test each geohash tile in the set of geohash tiles todetermine if the particular geohash tile is completely within theassociated polygon (e.g., without crossing the boundary of theassociated polygon). If the particular geohash tile is completely withinthe polygon, the IG module 112 can keep the geohash tile. If theparticular geohash tile is completely outside of the polygon, the IGmodule 112 can discard the particular geohash tile. If the particulargeohash tile is partially within the polygon (e.g. crossing the boundaryof the associated polygon,) the IG module 112 can break the particulargeohash tile into a plurality of geohash sub-tiles.

Subsequently, the IG module 112 repeats the above process using thegeohash sub-tiles. For example, the IG module 112 can determine, foreach of the plurality of geohash sub-tiles, whether the sub-tile iscompletely within the associated polygon. If the sub-tile is completelywithin the polygon, the IG module 112 can keep the geohash sub-tile. Ifthe sub-tile is completely outside of the polygon, the G1 module 112 candiscard the geohash sub-tile. If the sub-tile is partially within thepolygon, the IG module 112 can further break the geohash sub-tile into aplurality of smaller tiles and repeat this process. The IG module 112can perform this operation iteratively for each geohash tile to see ifit ‘fits’ (i.e. does not intersect) the polygon, and if not, itrecursively decreases the size of the geohash tile (e.g., increases theprecision) to achieve a fit.

In some embodiments, there is a maximum level of precision defined forthe geohash tiles (e.g., the smallest geohash tile that can be used tomodel the polygon), thereby providing a proper balance between thenumber of tiles and the level of fit for producing a good index. If atile is reduced to the minimum size (e.g., the maximum precision) butstill intersects the desired polygon, it is considered to be inside thepolygon and included in the index.

In some embodiments, a location identifier associated with a sub-polygoncan include a geohash code (e.g., a geohash code of the type defined inhttp://geohash.org/). A geohash code is a hierarchical spatial datastructure that subdivides a region into tiles. A geohash code caninclude a sequence of bits that substantially uniquely identifies alocation. In some cases, the sequence of bits can be encoded or canrepresent a sequence of characters. An example of a geohash code is acharacter sequence, “8z4fg.” In some embodiments, a set of geohash codescan exhibit hierarchical characteristics. For example, shorter geohashcodes can be associated with a lower precision (e.g., shorter geohashcodes are associated with larger geographic areas) whereas longergeohash codes can be associated with a higher precision (e.g., longergeohash codes are associated with smaller geographic areas). As aconsequence of the gradual precision degradation based on the number ofcharacters, nearby locations are often associated with similar prefixes.In some embodiments, the geohash codes that begin with the samecharacters can refer to the same geographic area. Two geohash codes thatshare a large number of prefix characters are associated with twolocations that are in proximity.

FIGS. 4A-4B illustrate properties of geohash codes and tiles inaccordance with some embodiments. FIG. 4A shows a geohash tile 402corresponding to a geohash code “8z4fg.” The geohash tile 402 iscentered on a geographical coordinate denoted by an X. X could representany geographical coordinate, for example, latitude=42 degrees North andlongitude=71 degrees West. FIG. 4B shows four geohash tiles 404A-404D.FIG. 4B also shows the geohash code associated with each tile (e.g.,“8z4fgf” is the geohash code for time 404A). The four geohash tiles404A-404D collectively cover the same area as the geohash tile 402. Infact, the four geohash tiles 404A-404D represent four sub-divisions ofthe geohash tile 402. The X at the center of FIG. 4B represents the samegeographical coordinate as the X shown in FIG. 4A.

Because the four geohash tiles 404A-404D represent four sub-divisions ofthe geohash tile 402, the geohash codes for the four geohash tiles404A-404D can be longer than the geohash code for the geohash tile 402,and the geohash codes for the four geohash tiles 404A-404D can sharecharacters with the geohash code for the geohash tile 402. For example,the geohash codes of the geohash tiles 404A-404D can be each sixcharacters long, whereas the geohash code the geohash tile 402 can befive characters long.

Furthermore, all geohash codes shown in FIG. 4B begin with the fivecharacter sequence “8z4fg”, which is identical to the geohash code ofthe geohash tile 402. This illustrates that geohash codes that beginwith the same sequence relate to the same geographical area. Since thegeohash codes of the geohash tiles 404A-404D begin with the samesequence as the geohash code of the geohash tile 402, the geohash codesof the geohash tiles 404A-404D are associated with tiles that fallwithin the geohash tile 402. Generally, if a geohash code corresponds toan original tile, then a concatenation of the geohash code with anothercharacter refers to a sub-tile within the original tile, as shown by theexample of FIGS. 4A-4B.

In summary, the use of hierarchical encoding schemes for locationidentifiers, such as geohash codes, offer useful properties, such as anarbitrary precision (e.g., by adding as many characters as needed), alocality (e.g., similar prefixes are associated with nearby positions),and the ability to reduce precision (or increase an area coverage) byremoving one or more characters from the end of the geohash code whilestill maintaining the spatial locality. These properties allow thedisclosed indexing system to limit the amount of high precision indexingto only areas that require that level of detail.

In some embodiments, a collection of location identifiers, such asgeohash codes (and their associated tiles) can be represented in a treestructure. FIG. 5 illustrates a tree of geohash codes in accordance withsome embodiments. The tree of geohash codes (also referred to as ageohash tree) 500 relates to the geohash tiles illustrates in FIGS.4A-4B. A geohash tree 500 can include branch nodes, such as a node 502,and leaf nodes, such as a node 504. A node is a branch node if itconnects to a lower node (either a lower branch node or a leaf node).For example, the branch node 502 connects to another branch node 506. Anode is a leaf node if it does not connect to any lower nodes. Forexample, the node 504 is a leaf node because it does not connect to anylower nodes. Some of the nodes in FIG. 5 can be associated with ageohash tile in FIG. 4. For example, the node 508 can be associated withthe geohash tile in FIG. 4A. As another example, the nodes 510, 512,514, and 504 can be associated with the geohash tiles 404A, 404B, 404C,and 404D, respectively.

FIGS. 6A-6D illustrate two collections of geohash tiles and theassociated tree in accordance with some embodiments. FIG. 6A shows asingle “large” geohash tile 602, whereas FIG. 6B shows a set of smallergeohash tiles, including tiles 604, 606. In FIG. 6B, the dashedperiphery is the same size as that of the large tile 602 shown in FIG.6A. FIG. 6B represents a case in which the large tile 602 does not fit apolygon well and so was split up into smaller tiles, including 604, 606,as previously discussed with respect to FIGS. 2-3. The single large tile602 can be represented as a tree structure that includes only one singleleaf node 608, as illustrated in FIG. 6C. On the other hand, the set oftiles shown in FIG. 6B can be represented as a tree structure thatincludes both branch node 608 and leaf nodes 610, 612, 614, 616, asillustrated in FIG. 6D.

Once the IG module 112 defines a polygon that describes a region ofinterest associated with an advertising campaign, the IG module 112 cangenerate one or more tree structures that describe the collection ofgeohash tiles in the polygon. The IG module 112 can repeat this processfor each set of geohash tiles in each polygon of interest.

In some embodiments, the IG module 112 can merge multiple geohash treesso that multiple geohash trees can be represented using a compactrepresentation. This feature can be useful when two or more computersare configured to generate multiple geohash trees in a distributedmanner, for example, simultaneously. At a high level, when two polygonshave intersecting geohash tiles, a lower precision geohash tile thatencompasses other higher precision geohash tiles can be marked as aleaf, while the higher precision geohash tiles are discarded from thegeohash tree. The net result is an optimized set of different precisiongeohash tiles that can be used to represent the set of disjoint polygonsthat make up a specified geo-targeted advertising campaign. This mergingoperation does not necessarily lose precision information because, ifregions not covered by the higher precision geohash tiles are within thepolygon according to a first geohash tree, there is no need todifferentiate regions in the higher precision geohash tiles and regionsoutside of the higher precision geohash tiles.

FIGS. 7A-7C illustrate a merging of the trees in accordance with someembodiments. FIGS. 7A-7B illustrate two trees. The first tree 702corresponds to a first polygon in the region of interest; the secondtree 706 corresponds to a second polygon in the region of interest. Thefirst tree 702 includes a geohash tile “4fg” 704, and the second tree706 includes subtiles of the geohash tile 704. Therefore, the region ofinterest includes both the geohash tile “4fg” 704, as indicated by thefirst tree 702, and the subtiles of the geohash tile 704, as indicatedby the second tree 706. The IG module 112 can merge these two trees togenerate a third tree 708 in which the subtiles of the geohash tile 704is subsumed by the geohash node 704. Therefore, the third tree 708 canrepresent the region of interest having both the first polygon and thesecond polygon with a less number of nodes in the tree compared to thecombined number of nodes in the first tree 702 and the second tree 706.

Subsequently, the IG module 112 can use the merged geohash tree togenerate an index system for the geohash tiles. The IG module 112 cangenerate the index system by walking down the geohash tree from the topbranch node to the leaf nodes in hierarchical order.

In some embodiments, the IG module 112 can reduce the resolution of ageohash tree to reduce the size of the geohash tree and to increase thequery speed of the index system associated with the geohash tree. Forexample, referring to FIG. 7B, the IG module 112 can truncate, in thegeohash tree 706, all nodes below the “g” node 704. This way, the IGmodule 112 can reduce the size of the geohash tree 706 at the expense ofreducing the resolution of the polygon represented by the geohash tree706.

FIGS. 8A-8B illustrate a mechanism for generating the geohash tile indexsystem in accordance with some embodiments. FIG. 8A illustrates ageohash tree 800 associated with three geohash tiles: a first geohashtile 802 with a geohash code “9q5d”, a second geohash tile 804 with ageohash code “9q5dt”, and a third geohash tile 806 with a geohash code“9q5dw.” The IG module 112 can walk down the geohash tree 800recursively to generate the geohash index system, as illustrated in FIG.8B. The IG module 112 can start from the top (e.g., the root node) ofthe tree 800, and, at each stage (e.g., each level of the tree or ageodesic distance level from the root node), emit an index correspondingto the value of the node at that stage.

For example, in the first step, the IG module 112 can generate “9” as anindex, since “9” is the value of the root node of the tree 800. Then theIG module 112 can walk down to the next node (e.g., the next level) andgenerate “q” as an index. Then the IG module 112 can walk down to thenext node and generate “5” as an index. Then the IG module 112 can walkdown to the next node and generate “d” as an index. Then the G1 module112 can walk down to the next node and generate “t” and “w” as indicesassociated with that level. In some embodiments, the IG module 112 canwalk the tree in a depth-first-search manner; in other embodiments, theIG module 112 can walk the tree in a breadth-first-search manner.

FIG. 88 illustrates the generated geohash index system based on thegeohash tree of FIG. 8A. In some embodiments, the geohash index systemcan be represented using a flat hierarchical data representation. Insome cases, the flat hierarchical data representation can include a jumptable. The jump table is, in effect, an unrolled representation (e.g.,rasterized representation) of the geohash tree 800. The unrolledrepresentation can be a single-layer data structure that can expeditethe search for relevant information. In other cases, the flathierarchical data representation can include a skip list.

In some embodiments, the geohash index system can be represented as aplurality of data structure nodes 808-816. Each data structure node cancorrespond to a set of nodes at the same level (e.g., the same distancefrom the root node) in the corresponding tree. For example, all nodes inlevel 3 (e.g., the number of shortest-path edges between the root nodeand a candidate node is 3), can be represented as a data structure node814 having three values: the length of the geohash nodes in the tree atthe current level 818, the value(s) 822 of the geohash nodes in the treeat the current level 818, and the number of “jumps” 820 to be performedto reach the data structure corresponding to the geohash nodes in thetree at the next level.

An alternative approach to encoding the data is to populate aprobabilistic data structure, such as a bloom filter. Both approacheshave merit and offer different tradeoffs. The flattened index approachdescribed above has the characteristics of giving a more deterministicanswer to the question, but at a potentially increased memory footprintwhen compared to the bloom filter approach. The bloom filter, on theother hand, is potentially more compact and would not require mergingtree structures but has a probabilistic margin of error and thus canreturn false positives and also has a greater impact of the processor'sability to prefetch memory pages.

An alternative approach to encoding the data is to use a hash table.

Once the IG module 112 generates the geohash index system, the IG module112 can store the geohash index system in the memory device 110.Subsequently, the query response (“QR”) module 114 can use the storedgeohash index system to serve location queries from clients 106.

FIG. 9 illustrates a process used by the QR module 114 for servinglocation queries in accordance with some embodiments. In step 902, theQR module 114 can be configured to receive a location query from aclient 106, requesting the QR module 114 to determine whether the client106 is within a polygon. To this end, the location query can include thelocation identifier of the client 106, indicating a location of theclient 106. The location identifier can take the form of a coordinate,for example, (longitude, latitude) pair. The client 106 can determineits location identifier based on a location determination mechanism. Thelocation determination mechanism can include a Global Positioning System(GPS) technique, a cellular tower triangulation technique, an InternetProtocol (IP) address-based location determination technique, and/or anyother suitable techniques for determining the location of the client106.

In step 904, the QR module 114 can be configured to convert the locationidentifier into a geohash code. In some embodiments, the QR module 114can be configured to generate the highest-precision query geohash codecorresponding to the location identifier (e.g., a geohash code that mostprecisely identifies a location associated with the locationidentifier.) In some embodiments, the precision of the query geohashcode can be higher than the maximum precision level of geohash codessummarized by the geohash index system.

In step 906, the QR module 114 can compare the query geohash code to thegeohash index system, and in step 908, the QR module 114 can determine,based on the comparison, whether the received location identifier iswithin a polygon modeled by the geohash index system. If the receivedlocation identifier is within the polygon, then in step 910, the QRmodule 114 can provide the identifier of the polygon that matched to thelocation identifier (e.g., so as to match the received locationidentifier with a particular advertising campaign). If the receivedlocation identifier is not within the polygon, then in step 912, the QRmodule 114 can indicate that the received location identifier does notcorrespond to the polygon. In some cases, in step 910, the host server102 can cause an advertisement associated with that polygon to be sentto the client 106. In some embodiments, this system allows suchprocessing for multiple location identifier received from multipleclients 106 to be performed quickly to determine whether the locationidentifiers provided by the client devices 106 are in any of thepolygons.

In some embodiments, in step 908, the QR module 114 can determinewhether the received location identifier is within an polygon modeled bythe geohash index system by comparing the query geohash code of thelocation identifier to the geohash index system. In some cases, the QRmodule 114 can be configured to compare characters corresponding tolarger geohash tiles (e.g., lower-precision geohash tiles) beforecomparing characters corresponding to smaller geohash tiles (e.g.,higher-precision geohash tiles.) For example, the QR module 114 canretrieve the first character of the query geohash code and compare thefirst character to the root node (e.g., the highest node) in the geohashindex system, modeled by the jump table and offsets. If the firstcharacter of the query geohash code matches one of the root nodes in thegeohash index system, the QR module 114 can determine if the one of theroot nodes represents a leaf node. If so, the QR module 114 can indicatethat the query geohash code is associated with a polygon modeled by theindex system and move to step 910. If the one of the root nodes does notrepresent a leaf node, the QR module 114 can move to the next character(e.g., a character adjacent to the first character), and compare the newcharacter with values in one or more nodes coupled to the one of theroot nodes (e.g., one or more children of the one of the root nodes.)

This process is iterated until (1) the QR module 114 does not find amatch between a character and a value of the nodes in the level (e.g.,the depth level of the geohash tree) corresponding to the character, or(2) the QR module 114 reaches the leaf node. If, at any point in walkingdown the geohash tree, the QR module 114 reaches a node where thecharacter of the query geohash code does not match the values in thegeohash index system, then the QR module 114 can declare a no-match andproceed to step 912. If the QR module 114 reaches the leaf node and thevalue of the leaf node matches a corresponding character in the querygeohash code, then the QR module 114 can indicate a match between thequery geohash code and the geohash index system, and proceed to step910. If the QR module 114 reaches the leaf node and the value of theleaf node does not match a corresponding character in the query geohashcode, then the QR module 114 can indicate a no-match between the querygeohash code and the geohash index system and proceed to step 912.

FIG. 10 illustrates a process for comparing a query geohash code to ageohash index system in accordance with some embodiments. In thisexample, the QR module 114 can communicate with the geohash index system1002 to determine whether a query geohash code “9q5f” 1004 is within apolygon modeled by the geohash index system 1002. In the first step, theQR module 114 can take the first character “9” of the query geohash code1004 and compare it against the root data structure 808 of the geohashindex system 1002. Since the value of the first character “9” matchesthe value of the root data structure 808, the QR module 114 can moveonto the second data structure 810. In the second step, the QR module114 can take the second character “q” of the query geohash code 1004 andcompare against the second data structure 810 of the geohash indexsystem 1002. Since the value of the second character “q” matches thevalue of the second data structure 810, the QR module 114 can move ontothe third data structure 812.

In the third step, the QR module 114 can take the third character “6” ofthe query geohash code 1004 and compare against the third data structure812 of the geohash index system 1002. Since the value of the thirdcharacter “6” does not match the value of the third data structure 812,the QR module 114 can determine that the query geohash code 1004 is notwithin the polygon modeled by the geohash index system 1002.

If, instead, the query geohash code is “9q5dt”, then the QR module 114will find a match at each data structure node in the geohash indexsystem 1002, and therefore, the QR module 114 would indicate that thelocation corresponding to the query geohash code is “9q5dt” is withinthe polygon modeled by the geohash index system 1002.

In some cases, a single comparison between the query geohash code andthe geohash tree can be sufficient reveal whether the receive locationidentifier is within a polygon. For example, if the query geohash codeof the location identifier lies within a tree having only a single leafnode, then the comparison of the first character of the query geohashcode to the tree structure can reveal a hit and it will be known thatthe client 106 is located within an area of interest. FIG. 11Aillustrates a scenario in which a single comparison can reveal a hit inaccordance with some embodiments. In FIG. 11A, the rectangle 1102corresponds to a single geohash tile, which is represented as a treestructure containing only a single leaf, as illustrated in FIG. 6C. TheX in FIG. 11A represents the location of the client 106 from which thelocation identifier is received. Due to the nature of query geohashcodes, the first character of the client's geohash code is identical tothe first character of the geohash code corresponding to the geohashtile 1102. Therefore, a comparison of the first character of theclient's query geohash code to the top level of the geohash tree canreveal a match.

In some cases, multiple comparisons between the query geohash code andthe geohash tree may be needed to reveal whether the receive locationidentifier is within a polygon. FIG. 11B illustrates a scenario in whichmultiple comparisons may be needed to reveal a hit in accordance withsome embodiments. In FIG. 6B, the set of geohash tiles is notrepresented by a single leaf. Rather, the geohash tree for that set oftiles includes multiple nodes, some of which are branches and others ofwhich are leafs, as illustrated in FIG. 6D. Therefore, the process ofdetermining whether the receive location identifier is within an polygonincludes comparing the query geohash code of the location identifier tothe geohash tree, one character at a time, from the top node of thegeohash tree to the bottom node of the geohash tree. If the first (e.g.,the most significant) character of the query geohash code matches one ofthe geohash trees in the index system, then the query geohash code iscompared against that tree structure's lower nodes, one node at a time.

Once the QR module 114 identifies at least one character in the querygeohash code that is not represented by the geohash index system, thenthe QR module 114 can move to step 914, indicating that the locationidentifier is not within an polygon. Any mismatch means the phone doesnot lie within the area of interest. On the other hand, if the QR module114 reaches the leaf node and the character in the leaf node matches thecorresponding character in the query geohash code, then the QR module114 can indicate that the location identifier is within the polygonmodeled by the geohash tree.

In some embodiments, the index system (e.g., the geohash tree) isdesigned to yield fast comparison performance, returning an answer inmicroseconds using a single core of a commodity server. In someembodiments, the index system can be designed to be re-entrant, solookups can scale out and take advantage of all available cores in thesystem without any adverse performance impacts due to lock conflicts.

In some embodiments, the index system can include information onpolygons corresponding to each geohash tile modeled by the index system.For example, the IG module 112 can determine a list of all polygons thatincludes a particular geohash tile, and associate that list to the leafnode corresponding to the particular geohash tile. This way, the indexsystem can maintain a correspondence between a geohash tile and allpolygons that includes the geohash tile. Subsequently, when the QRmodule 114 finds a match between a query geohash code and the indexsystem, the QR module 114 can return not only an identifier associatedwith the polygon, but also the specific polygons within the polygon thatcontributed to the match between the query geohash code and the indexsystem.

In some embodiments, a polygon can include one or more groupidentifiers. Group identifiers, can, for example relate to a campaignfor advertisements. For example, a campaign can include a plurality ofpolygons that collectively define areas to which a particularadvertisement campaign can be targeted. Each campaign can be associatedwith an identifier that identifies the associated advertisement. In someembodiments, an index system corresponding to a campaign can be storedin a single file. Each campaign file may contain many thousands ofindividual polygons (also referred to as geofences). For example, acampaign file can include all McDonalds' locations within a 10 km radiusof New York Penn Station.

In some embodiments, the IG module 112 can be configured to mergemultiple indices into a single index. In some embodiments, the IG module112 can be configured to remove a group from an existing index system.For example, the IG module 112 can traverse the existing index system(e.g., the tree), remove geohash codes associated with the group to beremoved, and recursively rebuild the portion of the existing indexsystem (e.g., a sub-tree) with the remaining geohash codes.

In some embodiments, the IG module 112 can provide the geohash indexsystem to the client 106 so that the client 106 can directly servelocation queries from other devices, such as mobile devices. In somecases, the IG module 112 can use a delta compression technique toprovide only modified parts of the geohash index system to the client106. The client 106 can use double buffering techniques to change itscurrent index system to bring it up to date with the new geohash indexsystem, without impacting existing query performance. For example, theclient 106 can maintain the current index system in memory and then loadthe new index system into memory while still processing requests bybased on the current index system. Once the new index system is fullyloaded into memory and ready to respond to queries, a pointer to thecurrent index system can instead reference the new index system such therequests are processed by referencing the new index system. Once thatstep is complete, the current index system can be deallocated frommemory. To accommodate these processes, it may be desirable for theclient 106 to have enough memory to store both the current index systemand the new index system.

In some embodiments, the host server 102 can provide an applicationprogramming interface (API) or web interface to allow advertisementservice entities to create a geohash index system for advertisement. Forexample, the API or web interface can allow the entities to generate agroup using simple query criteria such as ‘within a 1 mile radius ofbusinesses of type x in region y’. Once the entities select one or morepolygons that represent the advertisement group, the host server 102 canuse the above described method to generate the index system for thegroup. The index system can be represented as an index file. Then thehost server can transmit the index file to clients 106 (e.g., group(e.g. campaign) owner/advertisement networks machines/servers) with a QRmodule 114 so that the index file can be incorporated into the existingindex system in the client 106. This allows the QR module 114 in theclient devices 106 to directly serve the location queries from mobiledevices, instead of requesting the host server 102 to resolve thelocation queries.

In some embodiments, the IG module 112 can be configured to generate anindex system that is capable of returning a set of polygons intersectingwith a particular location. Such an index system can be useful in avariety of applications. In particular, such an index system canfacilitate a mechanism for providing information and groupingidentifiers of a particular location, collectively referred to as apayload data of a particular location. For instance, the QR module 114can use such an index system to determine one or more identifiers ofpolygons associated with the particular location and to use the one ormore identifiers of polygons to retrieve the payload data for theparticular location from a database.

More particularly, a grouping identifier can be associated with a groupof polygons to be represented together. The grouping identifier can beuseful to associate the same property to each of the polygons identifiedin the group of polygons. For example, an advertising campaign by Carl'sJr can target its advertisement to users who are near either aMcDonald's restaurant or a Burger King restaurant. In this case, theadvertising campaign can be tagged with a campaign identifier “carls”;one or more polygons associated with the McDonald's restaurant can betagged with a grouping identifier “mcd”; and one or more polygonsassociated with the Burger King restaurant can be tagged with a groupingidentifier “bk”. Furthermore, the grouping identifiers “mcd” and “bk”can be associated with the advertising campaign identifier “carls.”Subsequently, when an advertiser wants to post advertisements forCarl's, the advertiser can use the association between the campaignidentifier “carls” and the grouping identifiers “mcd” and “bk” toidentify all polygons to be associated with the advertisement campaign.

FIG. 12 illustrates a process for building an index system that iscapable of returning a set of polygons intersecting with a particularlocation in accordance with some embodiments. The index system canrepresent one or more regions of interest, where each region of interestcan include one or more polygons, and each polygon can be associatedwith a unique polygon identifier. The polygon identifier can include astring of characters, e.g., including numbers, which refers to aspecific polygon. The polygon identifier can be a UUID having, forexample, 128 bits, or an integer having, for example, 32 or 64 or someother number of bits. The polygon identifier can point to a specificentity of interest, for example, a specific McDonald's restaurant at aspecific address rather than McDonald's restaurants in general, whichmay be represented by an index or a group identifier.

When the IG module 112 is configured to generate an index system for oneregion of interest, the IG module 112 is configured to generate an indexsystem for that region by iterating steps 1202-1206. When the IG module112 is configured to generate an index system for more than one regionof interest, the IG module 112 is configured to generate an index systemfor each region independently by iterating steps 1202-1206, andconsolidate the index systems for each region as a post-processing stepin step 1208.

In some embodiments, the index system for a region can have a treestructure. Therefore, the index system for a region can be referred toas an index tree. A node in the index tree can be associated with asub-region of a region. Each node in the index tree can also beassociated with one or more identifiers of polygon(s) that intersectwith the sub-region associated with the node.

In some embodiments, the IG module 112 is configured to process theindex tree so that one or more polygon identifiers associated with anode can be represented succinctly. For example, the IG module 112 has amechanism for declaring a particular polygon identifier as a leafidentifier. When the IG module 112 declares a particular polygonidentifier as a leaf identifier at a particular node, then all childrennodes of the particular node are deemed to be associated with theparticular polygon identifier. This way, the IG module 112 obviates theneed to explicitly associate the leaf identifier with every child node,thereby reducing redundant associations of polygon identifiers in theindex tree.

More particularly, in step 1202, the IG module 112 is configured torepresent (e.g., tessellate) a polygon in a region using a plurality oftiles (e.g., sub-polygons). A sub-polygon is designed to cover an areawhose size depends on a predetermined level of precision associated withthe sub-polygon. For example, when the precision is low, the sub-polygoncovers a large area; when the precision is high, the sub-polygon coversa small area.

The IG module 112 is also configured to associate a sub-polygon with anidentifier of the polygon from which the sub-polygon is derived. Forexample, when a polygon is divided into 32 sub-polygons, each of thesub-polygons is associated with a polygon identifier of the originalpolygon. If a region includes more than one polygon, this process isrepeated for each polygon in the region. Therefore, a single sub-polygoncan be associated with a plurality of polygon identifiers. Subsequently,the sub-polygons used to represent polygons in the region can be groupedtogether to represent the region.

In step 1204, the IG module 112 is configured to recursively subdividethe region into sub-regions and associate each sub-region with a polygonidentifier covering the sub-region. More particularly, the IG module 112is first configured to identify one or more unique identifiers ofpolygons in the region. Then, the IG module 112 is configured toiteratively subdivide the region into sub-regions (and sub-regions intosmaller sub-regions), and assign one or more of the unique polygonidentifiers to a sub-region if the sub-region intersects with polygonsrepresented by the unique polygon identifiers. Since each sub-polygon isassociated with one or more polygon identifiers, the IG module 112 candetermine a set of polygon identifiers associated with each sub-region.

As the IG module 112 iteratively subdivide a region into sub-regions(and sub-regions into smaller sub-regions), the IG module 112 can buildan index tree corresponding to the region. FIGS. 13A-13D illustrate aprocess of building an index tree corresponding to a region inaccordance with some embodiments.

FIG. 13A illustrates a region 1300 that includes a plurality of tiles(e.g., sub-polygons, illustrated as small squares), where each tile isassociated with a location identifier, such as a geohash code. Theregion 1300 can represent one or more polygons that are illustratedusing dotted tiles. For example, a dotted tile 1304 indicates a tilethat belongs to one or more polygons in the region 1300; an empty tile1306 indicates a tile that is outside of one or more polygons in theregion 1300. For the purpose of illustration, the following exemplarydescriptions deem the region 1300 to include a single polygon 1302, butthe descriptions are also applicable to cases in which the region 1300includes multiple polygons.

To generate an index tree for the region 1300, the IG module 112 caninstantiate an index tree 1308 with a single root node corresponding tothe entire region 1300. FIG. 13B illustrates the region 1300 and theindex tree 1308 having a single root node 1310 corresponding to theentire region 1300. Subsequently, the IG module 112 can subdivide theregion 1300 into two sub-regions 1312, 1314, and add nodes 1316, 1318corresponding to the sub-regions 1312, 1314. Also, the IG module 112 canassociate the nodes 1316, 1318 with polygon identifiers of polygons thatintersect with the sub-regions 1312, 1314, respectively.

Subsequently, the IG module 112 can determine whether a polygon coversan entire area represented by a sub-region 1312 or 1314. If so, the IGmodule 112 can mark the polygon identifier of that polygon as a leafidentifier for that sub-region (or a node corresponding to thatsub-region), which indicates that all sub-trees rooted at thatsub-region include that leaf polygon identifier. In the example shown inFIG. 13B, every tile in the sub-region 1312 includes the same polygonidentifier corresponding to the polygon 1302. Therefore, the polygon1302 covers an entire area represented by the sub-region 1312. Thus, thepolygon identifier corresponding to the polygon 1302 in the node 1316 isa leaf identifier at the node 1316.

In some embodiments, if all polygon identifiers associated with a nodeis a leaf identifier, then the IG module 112 can stop building the indextree 1308 for the sub-region corresponding to that node (e.g., stopsub-dividing the sub-region corresponding to that node). In the exampleshown in FIG. 138, since the region 1300 includes only a single polygon1302, all polygon identifiers associated with the node 1316 is a leafidentifier. Therefore, the IG module 112 can stop sub-dividing thesub-region 1312 corresponding to the node 1316. On the other hand, notevery tile in the sub-region 1314 includes the same polygon identifiercorresponding to the polygon 1302. For instance, some of the tiles inthe sub-region 1314 does not intersect with the polygon 1302. Therefore,the polygon identifier associated with the node 1318 is not a leafidentifier. Thus, the IG module 112 is configured to further sub-dividethe sub-region 1314.

FIG. 13C illustrates a division of the sub-region 1314 into sub-regions1320, 1322, 1324, and 1326. Because only the sub-regions 1324, 1326include a tile of the polygon 1302, the IG module 112 is configured togenerate only two additional nodes 1328, 1330 in the index tree 1308associated with the sub-regions 1324, 1326, respectively, and discardsub-regions 1320, 1322 from further processing.

Furthermore, the IG module 12 can stop sub-dividing the sub-region 1324corresponding to the node 1328. Every tile in the sub-region 1324includes the polygon identifier of the polygon 1302. Therefore, thepolygon identifier of the polygon 1302 in the node 1328 is a leafidentifier. Furthermore, since the region 1300 includes only a singlepolygon 1302, all polygon identifiers associated with the node 1328 is aleaf identifier. Therefore, the IG module 112 can stop sub-dividing thesub-region 1324 corresponding to the node 1328.

On the other hand, the IG module 112 is configured to further sub-dividethe sub-region 1326. Not every tile in the sub-region 1326 includes thepolygon identifier of the polygon 1302. For example, some of the tilesin the sub-region 1326 does not intersect with the polygon 1302.Therefore, at least one of the polygon identifiers in the node 1330 isnot a leaf polygon identifier. Therefore, the IG module 112 isconfigured to further sub-divide the sub-region 1326.

FIG. 13D illustrates a division of the sub-region 1326 into sub-regions1332, 1334, 1336, and 1338. Through a similar process as outlined above,the IG module 112 is configured to add two additional nodes 1340, 1342to the index tree 1308, corresponding to sub-regions 1336, 1338,respectively.

In some embodiments, once the IG module 112 completes the indexgeneration process, the IG module 112 can be configured to traverse theindex tree 1308 from the leaf nodes (e.g., nodes 1340, 1342) to the rootnode (e.g., node 1310) to reduce the number of polygon identifiersassociated with the index tree 1308. The IG module 112 is configured todetermine whether all children nodes of a particular node (also referredto as a parent node) share the same polygon identifier. If so, the IGmodule 112 is configured to remove that polygon identifier from allchildren nodes, associate the parent node with that polygon identifier,and declare that polygon identifier as the leaf identifier at the parentnode. This reduction process can reduce the number of polygonidentifiers at the highest precision nodes (e.g., nodes furthest awayfrom the root node).

In some embodiments, the IG module 112 can reduce a number of bits usedto represent a polygon identifier in the index tree. To this end, the IGmodule 112 is configured to present a polygon identifier in a child nodeas an offset into a set of polygon identifiers in the parent node. Forexample, suppose that a parent node is associated with three polygonidentifiers: [021y4bcfjkp26rsx, pr2swz25xyqebc13, fm0qrx36zmn79fjpq],and has a child node that is associated with two polygon identifiers:[021y4bcfjkp26rsx, fin0qrx36zmn79fjpq]. Instead of actually writing outthe polygon identifiers in the child node, the IG module 112 can beconfigured to represent the polygon identifiers in the child node as anindex into the three polygon identifiers in the parent node. Under thisscheme, the IG module 112 can represent the two polygon identifiers inthe child node as [1, 3]. This representation can reduce the number ofbits used to represent polygon identifiers in the index tree.

Once the index tree is constructed, the IG module 112 can encode theindex tree (e.g., the polygon identifiers in each node of the indextree, the set of leaf polygon identifiers) into an index system, asillustrated in FIG. 8B in accordance with some embodiments.

Once the IG module 112 completes the index system generation for aregion, the IG module 112 can encode all the payload data associatedwith the region so that the data associated with the region (or apolygon within the region) can be retrieved quickly. To limit themagnitude of the offsets/jump indexes encoded at each sub-region level(e.g., each level in the index tree), the IG module 112 is configured toencode each level's data into a separate substream, including asub-index or an independent portion of the index.

Subsequently, the IG module 112 can write out this substream data (foreach level in the index tree) at the head of the total payload datarepresenting the entire region represented by the index tree. The IGmodule 112 can write out all polygon identifiers represented within thegiven region. Then, the IG module 112 can encode the hierarchicalregion/sub-region index tree, using a technique such a geohash encoding.These operations can complete the index generation process and thepayload database generation process for a region.

If there are more than one regions of interest, the IG module 112 canrepeat steps 1202-1206 for each region of interest, and generate anindex system for each region. Once the index system for each region isconstructed, in step 1208, the IG module 112 is configured to merge theindex systems into a single master index system so that the singlemaster index system can represent all regions of interest. In someembodiments, the single master index system can have a tree structure,and the tree structure can be based on geohash codes. Each leaf node ofthe single master index system can correspond to a region-level indexsystem generated in steps 1202-1206.

The index generation process of FIG. 12 is beneficial becauseregion-level index systems can be generated in parallel using adistributed computing system. Since regions can be independent of oneanother, the IG module 112 can assign a single computer to generate anindex system for one region without worrying about an index system foranother region. This allows for a parallel computation of region-levelindex systems, thereby providing a computationally scalable mechanismfor generating indices for many regions of interest. Furthermore, theindex generation process of FIG. 12 allows the IG module 112 to quicklyupdate the index system by building and encoding the index tree of onlythe region that needs to be updated.

The QR module 114 can use the master index system generated by the IGmodule 112, as illustrated in FIG. 12, to respond to a location queryfrom a client. In particular, the QR module 114 can use the master indexsystem to determine one or more polygons intersecting a locationidentified in the location query and provide any payload data associatedwith the one or more polygons to the client.

FIG. 14 illustrates a process 1400 for responding to a location query inaccordance with some embodiments. In step 1402, the QR module 114receives the location query and extracts a location identifier, such asa [latitude, longitude] pair or a geohash code, from the location query.The location associated with the location identifier is referred to as atarget location. Then the QR module 114 can identify the region thatincludes the target location, and retrieve, from the master indexsystem, the region-level index system corresponding to that region.Subsequently, the QR module 114 can allocate memory space to hold theset of polygon identifiers represented by the region, as encoded in theindex tree corresponding to the region. The memory space can be used tohold identifier(s) of polygon(s) that intersect with the targetlocation.

In step 1404, the QR module 114 can walk down the region-level indexsystem to find sub-regions of the region that also intersect with thetarget location. As the QR module 114 traverses down the index tree, ateach node during the traversal, the QR module 114 can collect leafpolygon identifiers associated with the node. Then the QR module 114 cannarrow the potential set of potential leaf identifiers that might befound in subsequent iterations. For example, as the QR module 114 walksdown the node hierarchy of the index tree, the set of polygonidentifiers relevant to a particular node corresponding to a particularsub-region is restricted to the polygon identifiers associated with theparent node of the particular node. Once the QR module 114 reaches theleaf node of the region-level index system (e.g., the highest precisionlevel of the region-level index system), the QR module 114 can terminatethe traversal of the region-level index system. The resulting set ofleaf polygon identifiers represents the set of polygons intersecting thelocation identifier.

In step 1406, once the QR module 114 identifies all polygonsintersecting the target location, the QR module 114 can retrieve payloaddata associated with the polygons using their identifiers. For example,the QR module 114 can request a database table or a hash table toretrieve any data, such as the name or address, associated with aparticular polygon identifier. Subsequently, the QR module 114 canprovide, to the client that sent the location query, the set of polygonidentifiers associated with the target location and any retrieved dataassociated with the polygons.

While the foregoing embodiments have been illustrated primarily usinggeohash codes and geohash tiles, the foregoing embodiments can use otherlocation identification mechanisms as well.

For example, in any of the embodiments disclosed herein, a region can berepresented by any type of a location identifier associated with ahierarchical location identifier system, including, for instance, ahash-based location identifier and/or a quad tree-based locationidentifier. Under the hierarchical location identifier systems, aconcatenation of a location identifier, associated with a region, withone additional bit (or character) can refer to one of a predeterminednumber of sub-regions contained within the region. For instance, aconcatenation of a location identifier, associated with a region, withone additional bit can refer to one of 4 sub-regions, 8 sub-regions, or16 sub-regions contained within the region. Also, for instance, aconcatenation of a location identifier, associated with a region, withone additional sequence of bits or one additional character can refer toone of 4 sub-regions, 8 sub-regions, or 16 sub-regions contained withinthe region.

As another example, in any of the embodiments disclosed herein, a regioncan be represented by any type of a location identifier that can beassociated with a particular geographic/physical precision. Forinstance, a data structure, such as a probabilistic data structureincluding a bloom filter, may be associated with one of a predeterminedset of precisions (e.g. 1 m, 3 m, 5 m, and 10 m) and can encode alocation identifier associated with the one of the predetermined set ofprecisions in, for example, as few bits as possible.

In some embodiments, the client 106 can include user equipment of acellular network. The user equipment communicates with one or more radioaccess networks and with wired communication networks. The userequipment can be a cellular phone having phonetic communicationcapabilities. The user equipment can also be a smart phone providingservices such as word processing, web browsing, gaming, e-bookcapabilities, an operating system, and a full keyboard. The userequipment can also be a tablet computer providing network access andmost of the services provided by a smart phone. The user equipmentoperates using an operating system such as Symbian OS, iPhone OS, RIM'sBlackberry, Windows Mobile, Linux, HP WebOS, and Android. The screenmight be a touch screen that is used to input data to the mobile device,in which case the screen can be used instead of the full keyboard. Theuser equipment can also keep global positioning coordinates, profileinformation, or other location information.

The client 106 also includes any platforms capable of computations andcommunication. Non-limiting examples can include computers, netbooks,laptops, servers, and any equipment with computation capabilities. Theclient 106 is configured with one or more processors that processinstructions and run software that may be stored in memory. Theprocessor also communicates with the memory and interfaces tocommunicate with other devices. The processor can be any applicableprocessor such as a system-on-a-chip that combines a CPU, an applicationprocessor, and flash memory. The client 106 can also provide a varietyof user interfaces such as a keyboard, a touch screen, a trackball, atouch pad, and/or a mouse. The client 106 may also include speakers anda display device in some embodiments.

In some embodiments, the host server 102 can reside in a data center andform a node in a cloud computing infrastructure. The host server 102 canalso provide services on demand. A module hosting a client is capable ofmigrating from one server to another server seamlessly, without causingprogram faults or system breakdown. The host server 102 on the cloud canbe managed using a management system.

Other embodiments are within the scope and spirit of the disclosedsubject matter.

The subject matter described herein can be implemented in digitalelectronic circuitry, or in computer software, firmware, or hardware,including the structural means disclosed in this specification andstructural equivalents thereof, or in combinations of them. The subjectmatter described herein can be implemented as one or more computerprogram products, such as one or more computer programs tangiblyembodied in an information carrier (e.g., in a machine-readable storagedevice), or embodied in a propagated signal, for execution by, or tocontrol the operation of, data processing apparatus (e.g., aprogrammable processor, a computer, or multiple computers). A computerprogram (also known as a program, software, software application, orcode) can be written in any form of programming language, includingcompiled or interpreted languages, and it can be deployed in any form,including as a stand-alone program or as a module, component,subroutine, or other unit suitable for use in a computing environment. Acomputer program does not necessarily correspond to a file. A programcan be stored in a portion of a file that holds other programs or data,in a single file dedicated to the program in question, or in multiplecoordinated files (e.g., files that store one or more modules,sub-programs, or portions of code). A computer program can be deployedto be executed on one computer or on multiple computers at one site ordistributed across multiple sites and interconnected by a communicationnetwork.

The processes and logic flows described in this specification, includingthe method steps of the subject matter described herein, can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions of the subject matter describedherein by operating on input data and generating output. The processesand logic flows can also be performed by, and apparatus of the subjectmatter described herein can be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application-specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processor of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. The essential elements of a computer area processor for executing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto-optical disks, or optical disks. Information carrierssuitable for embodying computer program instructions and data includeall forms of non-volatile memory, including by way of examplesemiconductor memory devices, (e.g., EPROM, EEPROM, and flash memorydevices); magnetic disks, (e.g., internal hard disks or removabledisks); magneto-optical disks; and optical disks (e.g., CD and DVDdisks). The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

To provide for interaction with a user, the subject matter describedherein can be implemented on a computer having a display device, e.g., aCRT (cathode ray tube) or LCD (liquid crystal display) monitor, fordisplaying information to the user and a keyboard and a pointing device,(e.g., a mouse or a trackball), by which the user can provide input tothe computer. Other kinds of devices can be used to provide forinteraction with a user as well. For example, feedback provided to theuser can be any form of sensory feedback, (e.g., visual feedback,auditory feedback, or tactile feedback), and input from the user can bereceived in any form, including acoustic, speech, or tactile input.

The techniques described herein can be implemented using one or moremodules. As used herein, the term “module” refers to computing software,firmware, hardware, and/or various combinations thereof. At a minimum,however, modules are not to be interpreted as software that is notimplemented on hardware, firmware, or recorded on a non-transitoryprocessor readable recordable storage medium. Indeed “module” is to beinterpreted to include at least some physical, non-transitory hardwaresuch as a part of a processor or computer. Two different modules canshare the same physical hardware (e.g., two different modules can usethe same processor and network interface). The modules described hereincan be combined, integrated, separated, and/or duplicated to supportvarious applications. Also, a function described herein as beingperformed at a particular module can be performed at one or more othermodules and/or by one or more other devices instead of or in addition tothe function performed at the particular module. Further, the modulescan be implemented across multiple devices and/or other components localor remote to one another. Additionally, the modules can be moved fromone device and added to another device, and/or can be included in bothdevices.

The subject matter described herein can be implemented in a computingsystem that includes a back-end component (e.g., a data server), amiddleware component (e.g., an application server), or a front-endcomponent (e.g., a client computer having a graphical user interface ora web browser through which a user can interact with an implementationof the subject matter described herein), or any combination of suchback-end, middleware, and front-end components. The components of thesystem can be interconnected by any form or medium of digital datacommunication, e.g., a communication network. Examples of communicationnetworks include a local area network (“LAN”) and a wide area network(“WAN”), e.g., the Internet.

The terms “a” or “an,” as used herein throughout the presentapplication, can be defined as one or more than one. Also, the use ofintroductory phrases such as “at least one” and “one or more” should notbe construed to imply that the introduction of another element by theindefinite articles “a” or “an” limits the corresponding element to onlyone such element. The same holds true for the use of definite articles.

It is to be understood that the disclosed subject matter is not limitedin its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The disclosed subject matter is capable ofother embodiments and of being practiced and carried out in variousways. Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and should not beregarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, methods, and systems for carryingout the several purposes of the disclosed subject matter. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions insofar as they do not depart from the spiritand scope of the disclosed subject matter.

Although the disclosed subject matter has been described and illustratedin the foregoing exemplary embodiments, it is understood that thepresent disclosure has been made only by way of example, and thatnumerous changes in the details of implementation of the disclosedsubject matter may be made without departing from the spirit and scopeof the disclosed subject matter.

What is claimed is:
 1. An apparatus comprising: a processor andnon-volatile memory comprising a set of computer-readable instructions,wherein the processor is configured to execute the computer readableinstructions to: represent a region of interest with one or morepolygons; determine a plurality of sub-polygons that are containedwithin the one or more polygons, wherein each of the sub-polygons isassociated with a unique code; and generate an index system based on atleast a subset of the plurality of sub-polygons, wherein in response toreceiving a location identifier from a client device, the processor isfurther configured to execute the computer readable instructions to:compare a query identifier corresponding to the location identifier withthe index system to determine that the location identifier is within theregion of interest, wherein the step of comparing includes: comparing afirst set of bits of one or more bits in the query identifier,corresponding to a lower-precision sub-polygon, to bits in the indexsystem, corresponding to sub-polygons in the region of interest; andcomparing a second set of bits of the one or more bits in the queryidentifier, corresponding to a higher-precision sub-polygon, to bits inthe index system, corresponding to the sub-polygons in the region ofinterest; and provide a service associated with the region of interestto the client device over a communication network.
 2. The apparatus ofclaim 1, wherein the identifiers are based on a hierarchical encodingscheme.
 3. The apparatus of claim 1, wherein the index system comprisesan index tree, and in response to the first set of bits of the one ormore bits in the query identifier matches a first index of the indexsystem corresponding to a leaf node of the index tree, the processordetermines whether the query identifier is within the region ofinterest.
 4. The apparatus of claim 1, wherein the processor is furtherconfigured to process a polygon identifier associated with the queryidentifier and retrieved from the index system, determine a groupidentifier associated with the polygon identifier, and provide a serviceassociated with the group identifier to a client device over acommunication network.
 5. The apparatus of claim 1, wherein theprocessor is further configured to process a polygon identifierassociated with the query identifier and retrieved from the indexsystem, and initiate transmission of information associated with thepolygon identifier to a client device over a communication network. 6.The apparatus of claim 1, wherein the processor is further configured toperform the step of comparing the first set of bits of the one or morebits in the query identifier to the bits in the index system before thestep of comparing the second set of bits of the one or more bits in thequery identifier to the bits in the index system.
 7. The apparatus ofclaim 1, wherein the processor is further configured to provide theservice associated with the region of interest to a client device over acommunication network after determining that the location identifierprovided by the client device is within the region of interest.
 8. Theapparatus of claim 1, wherein the location identifier is associated withthe client device's location.
 9. A computer-implemented methodcomprising: representing a region of interest with one or more polygons;determining a plurality of sub-polygons that are contained within theone or more polygons, wherein each of the sub-polygons is associatedwith a unique code; and generating an index system based on at least asubset of the plurality of sub-polygons, wherein in response toreceiving a location identifier from a client device thecomputer-implemented method further comprises: comparing a queryidentifier corresponding to the location identifier with the indexsystem to determine that the location identifier is within the region ofinterest, wherein the step of comparing includes: comparing a first setof bits of one or more bits in the query identifier, corresponding to alower-precision sub-polygon, to bits in the index system, correspondingto sub-polygons in the region of interest; and comparing a second set ofbits of the one or more bits in the query identifier, corresponding to ahigher-precision sub-polygon, to bits in the index system, correspondingto the sub-polygons in the region of interest; and providing a serviceassociated with the region of interest to the client device over acommunication network.
 10. The method of claim 9, wherein theidentifiers are based on a hierarchical encoding scheme.
 11. The methodof claim 9, wherein the index system comprises an index tree, and inresponse to determining that the first set of bits of the one or morebits in the query identifier matching a first index of the index systemcorresponding to a leaf node of the index tree, determining whether thequery identifier is within the region of interest.
 12. The method ofclaim 9, further comprising processing a polygon identifier associatedwith the query identifier and retrieved from the index system,determining a group identifier associated with the polygon identifier,and providing a service associated with the group identifier to a clientdevice over a communication network.
 13. The method of claim 9, furthercomprising processing a polygon identifier associated with the queryidentifier and retrieved from the index system, and initiatingtransmission of information associated with the polygon identifier to aclient device over a communication network.
 14. The method of claim 9,further comprising performing the step of comparing the first set ofbits of the one or more bits in the query identifier to the bits in theindex system before the step of comparing the second set of bits of theone or more bits in the query identifier to the bits in the indexsystem.
 15. The method of claim 9, further comprising providing theservice associated with the region of interest to a client device over acommunication network after determining that the location identifierprovided by the client device is within the region of interest.
 16. Themethod of claim 9, wherein the location identifier is associated withthe client device's location.
 17. A non-transitory computer readablemedium having instructions executable by a data processing apparatus to:represent a region of interest with one or more polygons; determine aplurality of sub-polygons that are contained within the one or morepolygons, wherein each of the sub-polygons is associated with a uniquecode; and generate an index system based on at least a subset of theplurality of sub-polygons, wherein in response to receiving a locationidentifier from a client device the instructions are further executableby the data processing apparatus to: compare a query identifiercorresponding to the location identifier with the index system todetermine that the location identifier is within the region of interest,wherein the step of comparing includes: comparing a first set of bits ofone or more bits in the query identifier, corresponding to alower-precision sub-polygon, to bits in the index system, correspondingto sub-polygons in the region of interest; and comparing a second set ofbits of the one or more bits in the query identifier, corresponding to ahigher-precision sub-polygon, to bits in the index system, correspondingto the sub-polygons in the region of interest; and provide a serviceassociated with the region of interest to the client device over acommunication network.
 18. The medium of claim 17, wherein theidentifiers are based on a hierarchical encoding scheme.
 19. The mediumof claim 17, wherein the index system comprises an index tree, and inresponse to determining that the first set of bits of the one or morebits in the query identifier matching a first index of the index systemcorresponding to a leaf node of the index tree, the instructions arefurther executable by the data processing apparatus to determine whetherthe query identifier is within the region of interest.
 20. The medium ofclaim 17, wherein the instructions are further executable by the dataprocessing apparatus to process a polygon identifier associated with thequery identifier and retrieved from the index system, determine a groupidentifier associated with the polygon identifier, and provide a serviceassociated with the group identifier to a client device over acommunication network.
 21. The medium of claim 17, wherein theinstructions are further executable by the data processing apparatus toprocess a polygon identifier associated with the query identifier andretrieved from the index system, and initiate transmission ofinformation associated with the polygon identifier to a client deviceover a communication network.
 22. The medium of claim 17, wherein theinstructions are further executable by the data processing apparatus toperform the step of comparing the first set of bits of the one or morebits in the query identifier to the bits in the index system before thestep of comparing the second set of bits of the one or more bits in thequery identifier to the bits in the index system.
 23. The medium ofclaim 17, wherein the instructions are further executable by the dataprocessing apparatus to provide the service associated with the regionof interest to a client device over a communication network afterdetermining that the location identifier provided by the client deviceis within the region of interest.
 24. The medium of claim 17, whereinthe location identifier is associated with the client device's location.